As is described in our above-referenced co-pending parent application Ser. No. 925,297, assigned to the assignee of the present application, trunk circuits have particular characteristics and requirements which previously have involved the use of hybrid transformers; reference may be had to the description of such attributes of trunk circuits set forth in the above-referenced application, which application is incorporated by reference in the present application, for a detailed explanation of both the prior art and applicants' contribution to the art using a transformerless trunk circuit that involves a circuit configuration containing photoelectronic components.
Now, although the specific invention disclosed and claimed in our above-referenced co-pending application offers a significant improvement over conventionally configured trunk circuits containing hybrid transformers, we have also found that the signal cancellation effects described in our former application can also be obtained with the use of a somewhat simpler structure by which the photocoupled circuitry is replaced by an inexpensive transformer coupled stage.